e) 2021 - 79 Documents

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INHIBITIVE EFFECT OF AN ALCOHOLIC EXTRACT OF A SEAWEED SARGASSUM MUTICUM IN CONTROLLING CORROSION OF MILD STEEL IN 0.5 N HCL
(International Journal of Corrosion and Scale Inhibition, 2021-10-20) Jeslina, V; Kirubavathy, S J; Al-Hashem, A; Rajendran, S; Lacnjevac, C; Joany, R M
The inhibitive effect of an alcoholic extract of a seaweed, namely, Sargassum Muticum, in controlling corrosion of mild steel in 0.5 N HCl has been evaluated by weight loss method (immersion period 1 day) and electrochemical techniques such as polarization study and AC impedance spectra. The protective film has been investigated by AFM and Vickers Hardness test. Weight loss method reveals that 500 ppm of inhibitor offers 99% inhibition efficiency to mild steel immersed in 0.5 N HCl. The adsorption of inhibitor molecules on the metal surface follows Langmuir adsorption isotherm. The R2 value is very high, 0.998. Polarization study reveals that the corrosion potential is slightly shifted to anodic side. It is inferred that the inhibitor solution functions as mixed type corrosion inhibitor. In the presence of the inhibitor, the linear polarization resistance (LPR) increases and the corrosion current decreases. Because of the Blanket effect (formation of a protective film on the metal surface blocking the anodic sites and cathodic), electron transfer from the metal to the bulk of the solution is blocked. AC impedance spectra confirm the formation of a protective film on the metal surface. As the inhibitor concentration increases, the Rct value increases and the double layer capacitance (Cdl) decreases, the impedance increases and the phase angle increases due to the blocking effect on the metal surface. It is found to be a monolayer of protective film. The Vickers hardness of the inhibited metal surface is lower than that of polished metal but higher than that of corroded surface. The average roughness, RMS roughness and maximum peak-to-valley height of inhibited metal surface are lower than those of corroded metal surface but higher than those of polished metal surface. The outcome of the study may be used in pickling industry where HCl is used to remove rust and at the same time metal surface is protected.
LIRIOPE PLATYPHYLLA EXTRACT AS A GREEN INHIBITOR FOR MILD STEEL CORROSION IN SULFURIC ACID MEDIUM
(Taylor & Francis Online, 2021) Ill-Min, Chung; Venkatesan, Hemapriya; Seung-Hyun, Kim; Kanchana, Ponnusamy; Natarajan, Arunadevi; Subramanian, Chitra
The phytochemical components of the methanol extract of Liriope platyphylla (L. platyphylla) leaves were identified using UHPLC, and their antioxidant activities were studied. The impact of the L. platyphylla extract on the corrosion of mild steel by 1 M H2SO4 was assessed using electrochemical and gravimetric techniques. L. platyphylla exhibited concentration-dependent corrosion protection activity through a mixed-mode adsorption process, as revealed by polarization studies. Impedance measurements indicated the development of a protective film of the inhibitor, which was confirmed by morphology studies at the micro level with scanning electron microscopy (SEM) and at the nano level with atomic force microscopy (AFM). Fourier transform infrared (FT-IR) studies also confirmed the adsorption of the inhibitor film onto the mild steel surface.